The present invention is in the field of electric vehicles. Specifically, the present invention is related to electric motor axle assemblies used in electric vehicles.
Electric traction motors (including induction machines) have been in development for over one hundred years. Primary development has been for railways, for both heavy (600-1500 kW) and light traction (100-400 kW) applications. Due to the significant development, the traction motor family is probably the most advanced with regards to technology and performance. Generally, the global requirements for a traction motor focus on power range, specific power, quality of supply, vibrations, temperature range, geometry etc. and the performance in these areas illustrates the huge developmental effort that has been undertaken.
However, for off-road severe-duty applications, a new constraint has to be considered in the design process. The traction motor must develop very large torque at low speed and still maintain significant power at high speed. For this application the extremes of high torque/low speed and high power/high speed are more demanding than in a rail application. Thus, it becomes extremely clear that a new class of traction motors must be developed. Specific constraints concerning weight and allowable geometry further complicate the issue and an xe2x80x9cof the shelfxe2x80x9d solution does not exist yet. However, reconsideration of the pole switch variation method in light of today""s technology has provided an answer to this problem. Generally speaking, pole switch variation is a very old method (not in use today) but we consider that a combination between this method and modem inverter control in conjunction with state of the art electric machine technologies can match 100% of the severe-heavy duty vehicle requirements.
The present invention includes: (a) an electric motor axle assembly; (b) vehicles comprising an electric motor axle assembly; (c) a two-motor electric axle assembly; and (d) vehicles comprising a two-motor electric axle assembly.
In broadest terms, an electric motor axle assembly of the present invention comprises an electric motor; a gear shaft; and an output shaft. The electric motor has a pinion shaft extending therefrom. The electric motor is adapted to rotate the pinion shaft about a first axis. The pinion shaft comprises a pinion gear. The gear shaft defines a second axis at least substantially parallel to the first axis. The gear shaft has disposed thereon a first gear and a second gear such that rotation of the gear shaft about the second axis induces rotation in the first gear and in the second gear. The first gear is adapted to engage the pinion gear. The output shaft defines a third axis at least substantially parallel to the first axis and the second axis. The output shaft comprises a third gear. The third gear is adapted to engage the second gear. The output shaft comprises at least a portion of a constant velocity joint.
It is preferred that the electric motor axle assembly further comprises a brake mechanism. The brake mechanism is disposed along the first axis. That is to say, when activated the brake mechanism is capable of stopping the rotation of the pinion shaft caused by the electric motor.
It is further preferred that the electric motor axle assembly comprises a drive shaft. The drive shaft comprises a first end and a second end. The first end of the drive shaft is coupled to the constant velocity joint such that rotation of the output shaft induces rotation of the drive shaft. It should be noted that depending upon the type of constant velocity joint used, components of the joint may necessarily be disposed on the first end of the drive shaft with the remainder of the components disposed in the output shaft. A preferred constant velocity joint is a three-ball trunnion style CV-joint.
It is even more preferred that the electric motor axle assembly further comprises a second constant velocity joint functionally coupled with the second end of the drive shaft.
The present invention includes vehicles comprising at least one electric motor axle assembly as discussed above.
In broadest terms, a two-motor electric axle assembly of the present invention comprises a first electric motor assembly and a second electric motor assembly. The first electric motor assembly and the second electric motor assembly are arranged such that their respective output shafts are aligned with one another along an axis. The elements of the first and second electric motor assemblies are arranged so as to permit the two assemblies to be so aligned without mechanical interference from each other. It is most preferred that the first electric motor assembly and the second electric motor assembly are nested with respect to each other such that the first electric motor at least partially extends over the second output shaft and such that the second electric motor at least partially extends over the first output shaft.
The first electric motor assembly comprises a first electric motor; a first gear shaft, and a first output shaft. The first electric motor has a first pinion shaft extending therefrom. The first electric motor is adapted to rotate the first pinion shaft about a first axis. The first pinion shaft comprises, a first pinion gear. The first gear shaft defines a second axis at least substantially parallel to the first axis. The first gear shaft has disposed thereon a first gear and a second gear such that rotation of the first gear shaft about the second axis induces rotation in the first gear and in the second gear. The first gear is adapted to engage the first pinion gear. The first output shaft defines a third axis. The third axis is at least substantially parallel to the first axis and the second axis. The first output shaft comprises a third gear. The third gear is adapted to engage the second gear. The first output shaft may comprise at least a portion of a first constant velocity joint.
The second electric motor assembly comprises a second electric motor; a second gear shaft; and a second output shaft. The second electric motor has a second pinion shaft extending therefrom. The second electric motor is adapted to rotate the second pinion shaft about a fourth axis. The second pinion shaft comprises a second pinion gear. The second gear shaft defines a fifth axis at least substantially parallel to the fourth axis. The second gear shaft has disposed thereon a fourth gear and a fifth gear such that rotation of the second gear shaft about the fifth axis induces rotation in the fourth gear and in the fifth gear. The fourth gear is adapted to engage the pinion gear. The second output shaft is disposed along the third axis. The third axis being at least substantially parallel to the fourth axis and the fifth axis. The second output shaft comprises a sixth gear. The sixth gear is adapted to engage the fifth gear. The second output shaft comprises at least a portion of a second constant velocity joint.
It is preferred that the two-motor electric axle assembly further comprises a first brake mechanism. The first brake mechanism is disposed along the first axis. The first brake mechanism is adapted to brake the first electric motor.
It is even more preferred that the two-motor electric axle assembly further comprises a second brake mechanism. The second brake mechanism is disposed along the fourth axis. The second brake mechanism is adapted to brake the second electric motor.
It is more preferred that the two-motor electric axle assembly further comprise a first drive shaft. The first drive shaft comprises a first end and a second end. The first end of the first drive shaft is coupled to the first constant velocity joint such that rotation of said first output shaft induces rotation of said first drive shaft. It should be noted that depending upon the type of constant velocity joint used, components of the joint may necessarily be disposed on the first end of the drive shaft with the remainder of the components disposed in the output shaft. A preferred constant velocity joint is a three-ball trunnion style CV-joint.
It is most preferred that the two-motor electric axle assembly further comprises a third constant velocity joint. The third constant velocity joint is functionally coupled with the second end of the first drive shaft.
It is more preferred that the two-motor electric axle assembly further comprise a second drive shaft. The said second drive shaft comprises a first end and a second end. The first end of the second drive shaft is coupled to the second constant velocity joint such that rotation of the second output shaft induces rotation of the second drive shaft. It should be noted that depending upon the type of constant velocity joint used, components of the joint may necessarily be disposed on the first end of the drive shaft with the remainder of the components disposed in the output shaft. A preferred constant velocity joint is a three-ball trunnion style CV-joint.
It is most preferred that the two-motor electric axle assembly further comprises a fourth constant velocity joint. The fourth constant velocity joint is functionally coupled with said second end of the second drive shaft.
The present invention also includes vehicles comprising at least one two-motor electric axle assembly as discussed above.